1. BULLSHIT. He stated in the panel I showed you that "her powers are to strong" and then proceeded to say gear 4.
Luffy: " her powers to strong"
Ulti: " Ulti Meteor..."
Luffy: "Uh-Oh! Gear Four..."
Luffy found ulti strong enough for him to need to require g4 had the fight continued even though he already had advanced coO (future sight and advanced coA (internal destruction ryou)
2. ALSO BULLSHIT. It was mastered before his fight with kaido. Hence why he was able to hit kaido severely with red rock upon everyone arriving to the roof with kidd being shocked that physical blunt attacks could actually work on kaido lol. He then took it a step further adding advanced coc to his internal destruction ryou. To do that he had to already master the ability of ryou in the first place.
3. Ask luffy who stated In the panel that i stated that "she too strong" when facing ulti lol.
4. The numbers are weaker than the flying 6 yet luffy still needed g4 to one shot the number (luffy could defeat him in base just not oneshot him). This goes hand and hand with my point that luffy needed g4 against ulti even though he already had internal destruction ryou lol
5. His base form increased BEFORE fighting ulti. It then further increased again while he was fighting kaido. Current egghead base luffy is stronger than the base luffy that fought kaido. So it further begs to question why couldn't base luffy 1 tap awakened lucci. And if your answer is "Because of plot to move the narrative" that would also equally indicate that it was also "PLOT" that wrote lucci as being strong enough to require luffy to use g5 on lol.
It's why your assumption of PLOT works against you